I am told that the version 6.X upgrade on the 5000 has its own DHCP server and that this is a new feature. Our phones are still digital, so we don't use this feature yet. I assume you have an existing DHCP server handing out IP addresses to your phones from before the upgrade to 6.X.
But just this fact of a new DHCP server in the mix makes me wonder whether the phones don't know which server to get its address from?
Adam in DC